Hiring a Dev for Direction Finding & Passive Radar Software

We are currently looking for a dev or engineer to work on a short project that will involve developing easy to use software for passive radar and direction finding applications. The hardware will utilize low cost phase coherent RTL-SDR's. The project is paid and will probably last about a month (depending on your speed on work). It would suit a student, researcher or hobbyist with some spare time. If you are familiar with RTL-SDR's, C/C++/Python, have DSP experience, and ideally have experience with direction finding please apply with a short bio, CV and relevant experience to [email protected] for more information. If the project is successful there may be future work. Thanks!

Most of the passive coherent radar examples that I have seen online have been targeted toward detecting airplanes. As I understand the concept, one can gauge the distance/velocity of an object by the difference in timing/frequency of a signal received directly from a strong transmitter (for example an FM radio station) and the reflected signal. I believe one must use two directional antennas (one pointed directly toward the transmitter and one pointed away).

The key to this is having two receivers with the same clock controlling them.

I imagine the RTL-SDR.com is planning on releasing such hardware (indeed I seem to recall that being rumored or discussed for a while).

My big hope is that this will also work for other hardware, for example the limesdr. (Both receiver channels on the full-not-mini LimeSDR are driven by the same clock I believe).

But people have used FM for passive radar already.
e.g.https://www.youtube.com/watch?v=aNfTjyECo94
The frequency shift due to Doppler would be proportional to the velocity (and the height). And the variation in the round trip time would be proportional to slant range.

Only the RPS2 (and RSP2pro[metal case]) has a clockin/clockout so you would need two of them. And two of the cheaper plastic ones would set you back $366.25 (inc shipping) or $426.25 for 2x RSP2pro (metal case inc shipping) . Which is a bit pricey. On paper it should be possible to do passive radar with a LimeSDR USB costing $299 (+$15 for shipping), but I’ve not seen anyone do this yet, which is a bit odd. I would suggest 2x pre order LimeSDR Mini’s currently at $139 (and $10 shipping each), since they have a clockout and clockin (on the back of the PCB). So $16 cheaper than a LimeSDR USB with fully frequency independent RX channels and $68.25 cheaper than two plastic RSP2’s. But the price of the mini’s will increase by $20 very soon so that would be $24 more than a LimeSDR mini and $28.25 cheaper than two RSP2’s. Of course you could always buy two RSP1A’s ($224.35 inc shipping) desolder the TCXO from one and sharing one TCXO between both boards.

I personally think waiting and seeing what rtl-sdr.com’s hardware is, would be the best course of action. Since they are starting to work on software it means, they either have prototype hardware ready now or at least very soon.

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What is RTL-SDR

The RTL-SDR is an ultra cheap software defined radio based on DVB-T TV tuners with RTL2832U chips. The RTL-SDR can be used as a wide band radio scanner. It may interest ham radio enthusiasts, hardware hackers, tinkerers and anyone interested in RF.